The invention comprises a flexible tightening device, especially for medical use, with an arm comprising of several jointed elements, which can pivot against each other, in which the arm can be locked in the current present pivotal position of the locking element by means of a tightening element.
Flexible tightening device such as those which are well-known especially in the sphere of medicine, where they serve to secure a medical tool, for example a spatula in a wound opening during an operation. These well-known tightening devices are essentially in the form of spheres and pipes, which are pulled by a flex on the inside. In order to lock the arm in any given position, the cord is tightened, whereby a friction stop is created between the sphere and the pipes, which stiffens the arm in the installed position. A disadvantage of this flexible tightening device is that because of the cord running through the interior the cavities and the cord are almost impossible to clean.
One generic tightening device is known as the U.S. Pat. No. 897,349. With this known tightening device the individual jointed elements are constructed in three parts in the direction of the length and demonstrate at one end a ball joint and at the opposite end a socket joint to receive a ball joint. Both socket joint forming length pieces of each jointed element can be fastened to each other by two the length pieces penetrating bolts, whereby at the same time a shaft bearing the ball joint inside each length piece of a joint element may be fastened by means of bolts. Each jointed element of this known tightening device consists of three components, namely the two length pieces and the shaft bearing the ball joint. Very precise production techniques are required with little margin for error, since in the assembly of the jointed elements, it is of the utmost importance that the bores in both length pieces and in the shaft are in exact alignment with each other, so that these components can be connected to one another by means of bolts. Therefore, on the one hand, the individual jointed elements of this tightening device can only be manufactured exactly at great expense and on the other expensive manual work is required, in order to fit together the individual components of each jointed element. This therefore makes the production costs for such a well-known tightening device very high.
Starting from this position, the idea behind this invention was to create a flexible tightening device of the type named above, which on one side may be adjusted and locked on more than one side and is also simple to construct, in order to enable simple assembly and complete cleaning.
The solution to this task is supplied by the invention which is characterized by the fact that each jointed element demonstrates at one end a ball joint and at the opposite end a socket joint to receive a ball joint. In addition, each jointed element is constructed in two parts in its length element, whereby the individual length pieces are adjustable with each other for locking purposes.
By using the invention""s ball and socket joint links to connect the individual jointed elements it is possible to adjust the arms of the invention that can be tightened with as much freedom as possible. Furthermore it is possible to lock the arm in any of these positions simply, so that the shape of the ball joint is made through adjustment of the length pieces of each of the jointed element in relation to one another. The simple two-part construction of the jointed element without interior components and other cavities further eases the assembly and cleaning of the invention""s flexible tightening device.
In accordance with a favoured working form the invention is suggested, that the length pieces of the locking elements constructed in the length direction are constructed in z-form from the side view that on a length piece, a ball joint is connected to the lower part of the socket joint and with the other length piece of the same jointed element of the lower part of the ball joint with the upper part of the socket joint.
For the opposite side adjustment of the length parts of a jointed element, the jointed element demonstrates a joint axle for both length pieces. These joint pivot axles ensure that on one hand the ball joint piece and the socket joint element of each length piece are adjusted and on the other the adjustment of the length pieces to one another follows in the same way.
The pivotal axis for the length pieces of each jointed elements is constructed in the middle of the jointed element and at the level of the lengthways cut through the ball and socket joint, which are so constructed that the length parts can be pivoted against one another with the result that the ball joint and the socket joint can be expanded to an angle or aperture xcex1 between the length parts. Through the opening of the socket joint, the ball joint is automatically expanded so that the same degree is expanded that will lead to an adjustment in the socket joint, in which the ball joint rests. This opposite adjustment leads to the locked position of the flexible arm in the chosen pivotal position.
Furthermore, it is suggested with the invention that the angle of aperture from the proximal jointed element to the distal jointed element from jointed element to joint element is represented by
xcex1prox greater than xcex1n greater than xcex1n+1 greater than  . . .  greater than xcex1dist≅0
In order to guide the jointed elements to the opposite adjustment on one hand and on the other to limit the angle of pivot, a through bore is constructed at right angles to the length part of the ball joint through the spherical equator of each jointed elements. In this bore for each length part of the ball joint a protruding pin may be inserted from outside above the outer surface of the ball joint, which in the condition when it is linked with another jointed element is guided in a groove constructed in the socket joint.
For the adjustment and tightening of the flexible arm, a handle forming a tightening element can be locked to the proximal end of the arm forming a jointed element, by which the proximal socket joint is expandable.
Finally, it is suggested with the invention, that at the jointed element the distal element of the arm a tool can be attached.